[SFDXA] Skyhighgain Coaxial Cable

Thu, 28 Mar 2002 19:36:12 -0500

With this cable you dont actually need a transmitter!

----- Original Message ----- 
From: "Alan Harp" <[email protected]>
To: "Bill Marx" <[email protected]>
Cc: "aSFDXA" <[email protected]>
Sent: Thursday, March 28, 2002 7:19 PM
Subject: Re: [SFDXA] Skyhighgain Coaxial Cable

> I suppose if your cable is not properly terminated the reflected power will
> come back and blow up your rig and set your house on fire.
> 
> Bill Marx wrote:
> 
> > I copied this from the R-390 List: - Bill W2CQ
> >
> > Please read and heed the following Consumer Safety Alert:
> >
> > The recent popularity of a new antenna cable called Skyhighgain Coax has
> > created a safety problem for users and a nightmare for firefighters.
> > SHGC was developed theoretically by Tricenters Experimental
> > Laboratories, Inc., as a signal-boosting element for use in radio and
> > television transmission lines.  Scientists at TELI discovered that when
> > a bias voltage is applied to the special material used to make SHGC, the
> > effect was incredible.  Instead of simply reducing signal loss, the
> > signal strength increased!
> >
> > Amplification of RF signals in the new coaxial transmission cable was
> > actually greater than 3 db (decibels) per meter per meter.  (Please read
> > that again.)
> >
> > In laymen's terms, that means that for every 10 centimeters a signal
> > travels through the cable the signal strength doubles!  Put 1 Watt of RF
> > energy into one end of a one meter length of SHGC and you get 2 Watts at
> > the other end (assuming you supply the bias voltage, of course).  At two
> > meters you get 4 Watts.  At three meters the signal strength increases
> > to eight Watts.  Doubling the power every meter the total effective
> > power of the signal exceeds 1,000 Watts by the time it has traveled only
> > 10 meters up the line.
> >
> > Now imagine what would happen if you had a 100-meter SHGC cable.  (The
> > actual figures are shown below.)
> >
> > In conventional transmission lines there is always some loss of signal
> > depending upon frequency and the electric characterists of the cable.
> > But with SHGC, instead of a loss, you get a gain in signal strength.
> > This is the stuff every radio engineer has dreamed of.
> >
> > But here's the problem:  The unwary (and mathematically challenged)
> > average user seems to think that if a short section of SHGC inserted in
> > his transmission line is good, then a longer one is better.  If one were
> > to, say, substitute SHGC for the complete run from the radio shack to
> > the top of a tower, the signal would have more energy than the cable (or
> > the antenna) could withstand.
> >
> > Designed to be used in short sections between standard coax and the
> > antenna, SHGC is not currently available, pending the resolution of
> > certain limiting manufacturing capabilities.  Some reports have
> > surfaced, however, that a few samples of the hot-pink colored coax have
> > somehow slipped past reality checkpoints and made their way into the
> > Amateur community.  Without official spec sheets and installation guides
> > SHGC poses a significant hazard to the uneducated.
> >
> > The following table dramatically illustrates the danger of using too
> > much Skyhighgain Coax in any transmission line:
> >
> > Length of Coax / Power Output
> >
> >      1 meters - 2 Watts
> >      2 meters - 4 Watts
> >      3 meters - 8 Watts
> >      4 meters - 16 Watts
> >      5 meters - 32 Watts
> >      6 meters - 64 Watts
> >      7 meters - 128 Watts
> >      8 meters - 256 Watts
> >      9 meters - 512 Watts
> >      10 meters - 1,024 Watts
> >      11 meters - 2,048 Watts
> >      12 meters - 4,096 Watts
> >      13 meters - 8,192 Watts
> >      14 meters - 16,384 Watts
> >      15 meters - 32,768 Watts
> >      16 meters - 65,536 Watts
> >      17 meters - 131,072 Watts
> >      18 meters - 262,144 Watts
> >      19 meters - 524,288 Watts
> >      20 meters - 1,048,576 Watts
> >      21 meters - 2,097,152 Watts
> >      22 meters - 4,194,304 Watts
> >      23 meters - 8,388,608 Watts
> >      24 meters - 16,777,216 Watts
> >      25 meters - 33,554,432 Watts
> >
> > As you can see, by the time you reach only 20 meters, the signal power
> > has exceeded a million Watts!  Assuming your facility's commercial power
> > mains could handle the load, the signal would exceed 30 million Watts at
> > only 25 meters from the transmitter.
> >
> > Of course, most power main breakers would trip long before the million
> > Watt level, but once the signal starts up the transmisison line the peak
> > envelope power (PEP) climbs so fast that there is a possibility that the
> > circuit breakers would either fuse or the electric current would simply
> > jump the breaker's open switch gap and power would continue to increase
> > until the primary main lines evaporated in what could only be described
> > as a bolt of artificial lightning, showering every surrounding structure
> > with hot plasma and sparks.
> >
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> 
> 